Conventional identity verification systems using biometric measures (such as, for example, signatures) to verify identity are typically divided into an enrollment phase and an identity verification phase. During the enrollment phase, an individual provides proof of identity (such as a driver's license) and one or more samples of a biometric measure. In one conventional system, an individual provides a plurality of signature samples. The signature samples are then used to generate a signature model. During later identity verification events, when the user proffers a signature as a form of identification, the signature model created using the signature samples is used to authenticate the signature presented during the identity verification event.
The problem with the conventional model is that values of a particular biometric measure typically vary over time. For example, an individual's signature may vary over time due to stress; posture; time pressure; distractions; fatigue, etc. When the biometric measure is facial appearance, the user's facial appearance may vary over time due to lighting conditions; facial expressions; fatigue; make up; weight gain and loss; hair growth, coloring and barbering, etc. An identity verification system that collects samples of a particular biometric measure at a single setting will not be able to generate a model for the biometric measure that reflects natural and statistically significant variations in the biometric measure. Without samples representing this variation, the system will be subject to higher false reject rates or higher false accept rates (undetected forgeries), or both.
Accordingly, those skilled in the art seek an identity verification system that creates a robust biometric measure model for use in identity verification events. In particular, those skilled in the art seek an identity verification system that creates and uses a biometric measure model that reflects natural and statistically significant variations in a biometric measure without unnecessarily delaying enrollment, or causing additional cost and inconvenience.